Possible dinosaur DNA has been found
scientificamerican.com
scientificamerican.com
So... what good does that do?
However, the article isn't clear about what they found. It says DNA, then it says there may not be a recoverable sequence. In that case nucleic acids would be a better term than DNA. Without more info on what stain they used to identify the "DNA", the implications of this research are hard to figure out.
They also applied a stain to the fossil and compared it to a stained emu bone here https://academic.oup.com/view-large/figure/200008014/nwz206f...
The issue I had with this is why can't we reassemble chunks of DNA like we can with a puzzle.
I'm certain specialized algorithms exist within DNA analysis for this reason. This isn't my field and there are already algorithms that exist on the top of my head that could solve this issue.
The main issue is that you'd have to find a LOT of DNA to build one complete strand and you wouldn't have one strand from one specific animal.
... but you'd have a rough picture.
65 million years would mean 130 halvings. Basically nothing left, then.
...but this may depend on environmental conditions. this must depend on average environmental temperature, right? Might dinosaur specimens in Antarctic or Arctic regions have experienced significantly lower average environmental temperatures? That could increase the half life significantly.
Maybe we'll find Cryolophosaurus DNA some day...
EDIT: the DNA degradation study specimen was in the south island of New Zealand, which had an average burial temperature of 13C.
Antarctica along the coast has an average annual temperature of about -10C. Further inland and at higher elevation, it's much colder and dryer. Both those increase DNA stability. It's not crazy to me that you might have a factor of 100x greater stability for specimens found where the average temperature over the last 65 million years was 20-40 degrees colder and also dryer.
EDIT AGAIN: Just to support what I said, it seems like a difference of average burial temperature of just 2.5 degrees C doubles the half-life of DNA (and this is multiplicative), so with a 20 degree difference in average burial temperature, that would be 8 doublings of half-life length (factor of 256), so instead of 500,000 years until the DNA was all broken up, you could have 128 million years. https://figshare.com/articles/_Predicted_DNA_half_life_for_v...
https://www.nature.com/news/dna-has-a-521-year-half-life-1.1...
Chemical decay tends to follow Arrhenius equation:
https://en.wikipedia.org/wiki/Arrhenius_equation#Equation
so indeed a difference of maybe 40C should lead to a difference in half life of about 20-30%. I think about 30 half lives (~10^-9 degradation factor) should be the limit of recoverability, so perhaps 521x30 = 15k years in normal conditions up to 521x30x1.25 = 20k years in low temperature.
Of course, other factors such as humidity could contribute as well to the half-life, and reactivity is a lot more complicated than the Arrhenius model in reality. But even then I would be surprised such a vast difference in reactivity outside of true cryogenic conditions (maybe even shielding from radiation?).
edit: your second edit is interesting :) is that curve polynomial or exponential?
This means significant differences in HL for minor temperature variations under e.g. Arrhenius model (consistent with your graph I think). To extrapolate it some parameters need to be estimated though, which sounds interesting, I'll get around to that later...
Nah, we just need to find roughly 2^130 dinosaur cells, and the rest is statistics...
It's not a completely solved problem as there are features of genomes that can make this process difficult or complicated (repetitive regions, highly heterozygous organisms, etc). Especially with short sequences.
We have technology right now that can allow us to sequence long fragments, but at lower quality and accuracy. There are a lot of tools out there that uses the longer, but lower quality sequences to scaffold the shorter, higher quality sequencing data.
Ie Pacbio - 10-15kb
Sanger sequencing, used for the human genome project 20 years ago is over 500 bases
That’s a good enough analogy for modern DNA sequencing.
The code of DNA is an image trapped in an opaque box. Instead of being able to image the complete picture of an organism’s DNA, you take thousands of identical images in opaque boxes, smash the boxes and their contents into tiny pieces to get bits of image out, then line up the now exposed fragments to see the original image.
It is the realignment that is the computationally expensive part of the process.
I literally clicked on the link because that was the only thing on my mind. Not joking.
That quote implied the former to me, so- there's not much to be learned from just nucleic acid soup
"... to this date, the possible preservation of original proteins and DNA in deep time has not been convincingly eliminated with data."
"Our data support the hypothesis that calcified cartilage is preserved at the molecular level in this Mesozoic material, and suggest that remnants of once-living chondrocytes, including their DNA, may preserve for millions of years."
https://academic.oup.com/nsr/article/doi/10.1093/nsr/nwz206/
DNA is not a radioactive material. It decays, but there's no absolute law like the radioactive decay, where the half life is the same for every microgram of the same substance everywhere in the world. The average half-life may be 500 years, but there can be situations where the DNA is exceptionally well preserved due to local circumstances. As a simple analogy: the average half life of a human settlement is, let's say 50 years. That means we should see absolutely no traces of human settlements older than 2000 years (40 half-lives). That is far from true.
No molecule is 100% stable... Every molecular bond will break eventually due to random thermal noise...
but:
Researchers in 2016 measured chloroplast DNA in marine sediment cores, and found diatom DNA dating back to 1.4 million years.[62] This DNA had a half-life significantly longer than previous research, of up to 15,000 years. Kirkpatrick's team also found that DNA only decayed along a half-life rate until about 100 thousand years, at which point it followed a slower, power-law decay rate.
Okay, so you're 1/45th of the way there.
And that's not even getting into the complex interaction between a mother and her unborn child, including cytoplasm, mitochondrial RNA, etc. It's not like an organism springs whole cloth from DNA alone.
We have animals now that are closely enough related to extinct animals that we could conceivably bring them back through incremental genetic modifications.
For example, if we wanted to bring back Direwolves, we could edit the DNA of a gray wolf maximally such that it can still be fertile and be born by a non-edited gray wolf. This would give you a wolf closer to a Direwolf and then you could repeat this process using each previous generation as the carrying mother for the genetically modified embryo.
If you were to clone a New Yorker thousands of years from now and put them in an exhibit in a Zoo marked "New Yorker", lots of people would be very impressed, even if they didn't start cooking New York-style pizza.
I don't think that's true. We raise animals without their parents all the time, both on farms and in zoos. The animals we end up with are still recognizably horses or rats or chimpanzees, with unique behavioural traits that could be studied for years. Even if you lose the social structure of mammoth society, you would still be bringing back something fascinating.
Animals that can be hatched from eggs have even less dependency on their mothers, too.
I have 16 chicks in the brooder that have never been around a chicken. They never will be around any but their 15 "siblings."
They're still acting like chickens, and they will continue throughout their lifetimes.
It's unlikely, we'll see.
And they tried really hard to get something out of the really good Mammoth DNA from Siberia. The blood was still liquid. No chance so far.
With today's technology could we create a creature from long ago with nothing more than it's DNA?
It’s harder the older the sample and vastly more difficult if few closely related species survive.
Dinosaurs have enough cultural prestige that it would make total sense to do it as a vanity project if the technology is there.
Similar to turning lead into gold -- there's enough cultural meaning built up around it that someone should do it before it really makes sense in a vacuum.
Even if we got really really lucky and found some that had spent most of its existence frozen deep in Antarctica or something, that would only open the potential of restoring a single dinosaur lineage and not the vast array of species depicted in Jurassic Park. That's total fantasy.
Using numbers taken from http://news.mit.edu/1994/safe-0105 for napkin-math:
Average background dose/year: 500 millirem
LD50 instantaneous exposure: 450000 millirem
LD100 instantaneous exposure: 600000 millirem
Radiation exposure of our dinoDNA sample: 65 million * 500 = 32.5 billion millirem.
Obviously there's a lot more to it than simple dose adding, but this gives you an idea of just what deep-time DNA recovery is up against.
Like hyperbovine mentioned, there are actually other effects that come in to play far sooner, but radiation puts (an additional) hard cap on things, and is easy to napkin-math.
Could you describe half life here? So suppose the strands are now small snippets. If you find enough, couldnt you overlap common parts and eventually re-construct the full length?
Being in amber might protect from moisture, but I think the temperature and temperature swings would still likely destroy it within thousands of years.
.. Except for the DNA that has survived and been passed down to living species today.
Also, immune problems I don't think would be a huge issue, the adaptive immune system has been around for a while.
On a more serious note, are egg sizes proportional to the size of the animal, or does the curve flatten after a certain size? I can't imagine an adult T-Rex dropping eggs that are 90cm across, for example, without either breaking them or making the shell impractically thick.
So huge dinosaurs had eggs that weren't much bigger than ostrich eggs, containing relatively tiny offspring. Maybe they would have been very cute. Or not, since baby birds often aren't that cute.
Since eggs had to be small, many dinosaurs utilized r-selection, like sea turtles for example, producing large numbers of eggs that only a tiny percent of which would survive to adulthood. This may also be why there were such ferociously efficient superpredator dinosaurs, because there were large numbers of relatively helpless juvenile dinosaurs scampering around to be preyed upon.
Some are trying to do this with chickens
Yet somehow camels or kangaroos seem to have no trouble living in each others environments.
In fact, you see a bit of the reverse - Banana skin rapidly decomposes in tropical forests where bananas grow, but take one to frigid Norway and drop a banana skin in a forest and you'll still be able to find it in 5 years, while local stuff is decomposing around it.
But I'm sure you can start there and find some interesting tangent that can very well turn out to be worth pursuing further.
Besides, the sequence alone is not the full state. You have to also consider expression and regulation and all that; epigenetics.
Could you normally have two viable lineages, each with the same DNA, and each with a different expression of that DNA which is stably conserved over many generations, purely due to womb environment, etc.? In other words, if you cloned a woolly mammoth using an elephant surrogate, might the great great great great grandchildren of this clone still have some characteristics that are due to having an elephant surrogate ancestor?
Or would there be a tendency to converge to a single stable expression due entirely to genetics?
It‘s obvious that in principle the answer could go either way, but I’m not sure whether that’s true in practice, with naturally occurring organisms and naturally occurring DNA sequences. For the sake of this question, one is also tempted to exclude post-natal “cultural” transmission, but it’s not clear that can be easily distinguished.
Or something like this? https://arxiv.org/abs/1712.06148
All right then.
As is common with science articles, the headline doesn't quite match reality.
I think samples need to be isolated and sequenced before we know what we're dealing with.
Has anyone seen any followups to this?
With modern sequencing technology, shouldn't they be able to detect strands of base pairs much shorter than in the past?
Its advocates almost without exception, do not give a shit about the facts, and you aren't going to sway them with another few pebbles added to the absolute mountain of evidence that their position is flawed.
Debating them like their position has merit and is reasonable is a hopeless waste of time, and is in fact exactly what they want because it puts their position on level footing with the scientific consensus.
All evidence and models across a large variety of disciplines points to the age of the fossils. Geological strata, carbon isotope ratios, phylogenetics, etc.
Feel free to present your evidence so that we can weigh in.
That said, I can give you a tasty nugget if you want. I reject using uniformitarianism (ad infinitum) as a scientific axiom. And I scoff at the arrogance of my fellow academics, especially for presenting stories such as these as fact.
Using scare quotes like that makes me totally confused what you're trying to say. If it's
I'm simply criticizing what passes for science these days.
then why not say so. The scare quotes give an impression you have a problem with all science, not just bad science, which I don't think you meant.
For a discussion of how poisonous to meaning this practice of using scare quotes can be, see David Stove's chapter Neutralizing Success-Words, an analysis of leading 20th C philosophers of science doing it. http://nekhbet.com/popper/chapter-01.html part 3. It's extremely enlightening and pretty funny, as Stove always is.
Not to me, it looks like the normal use of scare quotes. You could swap it with so called science. Stuff that people call science, which is not.
If someone doesn't like any science, why would they care about a distinction between science and so called science?
If you don't like that, then you don't like scare quotes at all, but then what's the problem with saying "so called blah"?